Strategem adds a number of new strategies to the game, that complement the stock strategies. Fully balanced towards stock values, these strategies should help you try out new play styles.
Reliable Technology: Do as the Russians do and build your spacecraft based on tried-and-tested technology instead of always coming up with new stuff. Unlocking new parts in the tech tree is more expensive, but your launch costs will be reduced.
Cutting Edge Research: Bigger is always better! Just like the Americans in the Space Race, put an emphasis on inventing new technology to make your future missions easier. While unlocking new parts in the tech tree will become cheaper, launch costs will increase as a result of your reliance on brand new equipment.
Local Supplier Preference: Sometimes you have to take one for the team. The opposite of Aggressive Negotiations, this strategy will have you pay more to unlock parts and build rockets out of them, but will get you a big bonus to your reputation as a result. By preferring local suppliers, you might be getting worse deals but you'll be creating more jobs and the public will love you for it.
Mass-Produced Parts: Why would you want to spend all that effort to build and return complicated reusable craft to get your investment back, when you can much easier send mass-produced, throwaway rockets into space. The opposite of Recovery Transponder Fitting, this strategy will reduce recovery costs, but also reduce your launch costs.